UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


TOPPING  AND   PINCHING  VINES 


BY 
FREDERIC  T.  BIOLETTI   and   F.  C.  H.  FLOSSFEDER 


BULLETIN  No.  296 

May,  1918 


UNIVERSITY    OF   CALIFORNIA  PRESS 
BERKELEY 

1918 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPEEIMENT  STATION  STAFF 

HEADS  OP  DIVISIONS 

Thomas  Foesyth  Hunt,  Director. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director ;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 

Charles  W.  Woodworth,  Entomology. 

Ealph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 
t Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

Walter  Mulford,  Forestry. 

W.  P.  Kelley,  Agricultural  Chemistry. 

H.  J.  Quayle,  Entomology. 

J.  B.  Davidson,  Agricultural  Engineering. 

Elwood  Mead,  Eural  Institutions. 

H.  S.  Reed,  Plant  Physiology. 

W.  L.  Howard,  Pomology. 
jFrank  Adams,  Irrigation  Investigations. 

C.  L.  Eoadhouse,  Dairy  Industry. 

O.  J.  Kern,  Agricultural  Education. 

John  E.  Dougherty,  Poultry  Husbandry. 

S.  S.  Eogers,  Olericulture. 

J.  G.  Moodey,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 


DIVISION  OF  VITICULTUEE  AND  ENOLOGY 
Frederic  T.  Bioletti  W.  V.  Cruess 

F.  C.  H.  Flossfeder  J.  E.  Zion 

G.  Barovetto  A.  E.  Way 


t  In  co-operation  with  office  of  Public  Eoads   and  Eural   Engineering,   U.   S. 
Department  of  Agriculture. 
t  In  military  service. 


TOPPING  AND  PINCHING  VINES 

By  FREDERIC  T.  BIOLETTI  and  F.  C.  H.  FLOSSFEDER 


It  is  a  common  practice  in  California  to  cut  off  the  ends  of  the 
growing  shoots  of  vines  during  the  late  spring  and  early  summer.  In 
a  few  vineyards  only  the  extreme  tip  is  removed,  but  in  many  a  large 
part  of  the  shoot  is  destroyed,  and  the  operation  is  often  repeated. 

In  most  cases  the  grape  growers  do  not  seem  to  have  a  very  clear 
or  logical  idea  of  why  they  do  this  and  there  are  theoretical  reasons 
for  believing  that  much  of  it  is  harmful.  These  reasons  are  discussed 
in  detail  in  our  Bulletin  241,*  and  also  the  various  forms  of  summer 
or  herbaceous  pruning  and  the  cases  in  which  they  are  useful. 

This  bulletin  gives  an  account  of  certain  experiments  which  have 
been  carried  out  at  the  University  Farm  to  test  the  practical  effects 
of  these  two  commonest  forms  of  summer  pruning,  topping  and 
pinching. 

Topping  consists  in  cutting  off  one,  two,  or  more  feet  of  the  grow- 
ing shoots  in  summer  or  autumn.  Pinching  is  removing  with  thumb 
and  finger  the  extreme  tip  of  the  growing  shoots  in  late  spring  and 
early  summer.  In  the  former,  a  considerable  amount  of  foliage  is 
removed ;  in  the  latter,  hardly  any. 

The  effects  claimed  for  pinching  are  delay  in  the  lengthening  of 
the  shoots  and  a  consequent  protection  from  wind  injury  and  a  more 
upright  growth  which  tends  to  shade  the  fruit  better  and  to  permit  of 
later  irrigation  and  cultivation.  When  done  before  blossoming,  it 
tends  to  cause  better  setting  of  the  fruit.  If  applied  to  the  first 
vigorous  shoots  it  tends  to  favor  the  growth  of  the  weaker  and  even  to 
cause  the  growth  of  buds  which  otherwise  would  have  remained 
dormant.  Both  of  these  effects  are  supposed  to  increase  the  crop. 
When  done  later,  it  encourages  the  growth  of  laterals  on  which  the 
second  crop  is  borne.  Whether  this  second  crop  is  wholly  a  gain  or 
whether  it  is  produced  at  the  expense  of  the  first  crop  does  not  seem 
to  have  been  determined.  Where  the  first  crop  is  a  failure  owing  to 
frost  or  other  causes  it  is  probably  a  clear  gain.  In  other  cases,  it  is 
doubtful,  especially  as  the  second  crop  is  usually  of  inferior  quality 
and  often  not  worth  harvesting.  The  production  of  laterals  is  some- 
times useful,  as  in  the  case  of  Sultanina,  because  they  supply  fruit 
buds  for  the  following  year,  making  it  possible  to  obtain  a  larger  num- 
ber of  fruit  buds  on  a  short  fruit  cane. 


*  Vine  Pruning  in  California,  Part  I,  Bui.  241,  College  of  Agriculture,  Berkeley, 
California,  pp.  30-39. 


372  UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 

The  effects  claimed  for  topping  are  similar.  It  cannot,  however, 
be  applied  before  blossoming,  so  that  it  cannot  be  used  to  promote 
' '  setting. ' '  Another  effect  claimed  for  topping  is  that  it  increases  the 
size  of  the  grapes.  This  seems  to  be  true,  but  at  the  expense  of  the 
sugar,  flavor,  and  color  of  the  fruit. 

The  weakening  effect  which  is  recognized  to  result  from  all  con- 
siderable removals  of  foliage  must  be  greater  in  the  case  of  topping 
than  of  pinching. 

To  test  some  of  the  claims  for  these  operations,  a  series  of  tests  has 
been  conducted  at  Davis  for  two  years.  The  points  investigated  were 
the  influence  on  the  quantity  of  the  crop,  the  influence  on  its  quality 
as  evidenced  by  the  sugar  contents  of  the  grapes,  and  the  influence  on 
the  vigor  of  the  vine  as  evidenced  by  the  annual  growth  of  wood. 

METHODS  AND  RESULTS  OF  EXPERIMENTS 

1.  Arrangement  of  the  Experiments. — Two  small  blocks  of  vines 
were  chosen  for  the  experiment.  One  consisted  of  10  rows  of  Carign- 
ane,  220  vines  in  all,  3  years  old  in  the  spring  of  1916 ;  the  other,  of 
10  rows  of  Tokay,  240  vines  in  all,  6  years  old  in  the  spring  of  1916. 
All  the  vines  were  strong,  healthy,  in  full  bearing  and  growing  in 
uniform,  deep  rich  soil  on  the  University  Farm  at  Davis. 

The  arrangement  of  the  experiments  was  as  follows : 

Carignane:  Rows 

No  summer  pruning  1]  16 

Pinched   once   12  17 

Pinched  three  times  13  18 

Topped  once  14  19 

Topped  three  times  15  20 

Tokay : 

No  summer  pruning 31  36 

Pinched  once  32  37 

Pinched  three  times 33  38 

Topped  once  34  39 

Topped  three  times  35  40 

Each  test  was  thus  made  in  duplicate,  both  with  the  Carignane 
and  with  the  Tokay.  Both  of  these  varieties  are  very  vigorous,  so  that 
they  might  be  expected  to  suffer  less  than  most  varieties  from  any  treat- 
ment of  a  weakening  nature.  They  are  both  regular  and  heavy  bearers 
under  ordinary  conditions  and  therefore  any  variations  in  the  crop 
might  well  be  ascribed  to  the  differences  in  summer  pruning  which 
were  the  only  differences  in  treatment  given. 


TOPPING  AND  PINCHING  VINES  ?>!'■'> 

2.  Length  of  Shoots  Removed. — In  pinching,  only  the  extreme  tip 
of  the  growing  shoot  was  removed,  sufficient  to  stop  temporarily  the 
production  of  new  joints  and  to  delay  the  growth  in  length.  Less 
than  one  inch  of  the  shoot  was  removed  each  time. 

After  the  first  pinching,  a  new  terminal  shoot  is  usually  formed 
from  a  side  hud  near  the  end  from  which  the  tip  has  been  removed. 
This  occurs  after  a  delay  of  about  a  week  or  more.  This  pinching 
stimulates  the  growth  of  laterals.  The  second  pinching  is  sometimes 
followed  by  a  new  terminal  growth  in  the  same  way  but  usually  results 
in  transferring  the  main  apical  growth  or  elongation  to  one  or  more 
strong  laterals.  At  the  third  pinching,  it  is  the  tips  of  these  laterals 
which  are  removed. 

In  topping,  from  one-fifth  to  one-fourth  of  the  length  of  the  shoot 
was  cut  off.  The  length  of  the  pieces  removed  varied  according  to 
the  condition  and  vigor  of  the  vine.  In  table  I  is  given  the  average 
length  of  these  pieces. 

TABLE  I 
Length  op  Shoots  Removed  in  Topping 

1916  1917 


l 

2 

3 

1 

2 

3 

cm. 

cm. 

cm. 

cm. 

cm. 

cm. 

Carignane  

48 

51 

37 

43 

43 

26 

Tokav  

65 

48 

53 

45 

47 

33 

Approximate  mean   (inches)   22  19  18  17  18  12 

The  average  length  of  the  tops  removed  for  all  cases  is  17.7  inches. 
It  was  about  19  inches  for  the  Tokay  and  16  inches  for  the  Carignane 
which  normally  has  shorter  canes.  In  1916  the  average  length  was 
about  20  inches  and  in  1917  about  16,  showing  a  less  rapid  or  vigorous 
growth  during  the  second  season.  The  third  topping  tends  to  remove 
shorter  pieces  on  account  of  the  slackening  of  growth  due  to  the 
approach  of  the  dormant  season  and  the  weakening  caused  by  previous 
toppings. 

3.  Number  of  Tips  or  Shoots  Removed. — The  average  number  of 
tips  removed  per  vine  for  each  operation  during  1917  was  31  in  the 
case  of  pinching  and  '23  in  the  case  of  topping. 

The  increase  in  the  number  of  removals  from  about  16  at  the  first 
operation  to  33  and  36  at  the  later  operations  indicates  the  increase  of 
growing  tips  due  to  the  development  of  laterals  and  the  growth  of 
the  shorter  and  later  starting  shoots.  The  number  of  tips  and  shoots 
removed  in  1916  averaged  30  per  vine  for  each  operation  and  25  in 
1917,  indicating  a  less  abundant  growth  for  the  latter  season. 


33 

53 

33 

29 

27 

12 

39 

52 

35 

41 

374  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

TABLE  II 

Number  of  Shoots  Eemoved  per  Vine 

1  2  3 

Carignane,  pinching,  1916  17 

Carignane,  topping,  1916  14  33  27 

Tokay,  pinching,   1916   

Tokay,  topping,  1916  17 

Carrignane,  pinching,  1917  18 

Carignane,  topping,    1917    : 18 

Tokay,  pinching,  1917  15 

Tokay,  topping,  1917  16 

Averages    16.4  33.3  35.7 

4.  Weight  of  Material  Removed. — In  pinching,  the  weight  of  mate- 
rial removed  is  extremely  small  and  was  not  measured.  It  is  so  minute 
that  any  effect  produced  by  the  operation  can  hardly  be  ascribed  to 
the  actual  loss  of  material. 

In  topping,  on  the  other  hand,  a  considerable  weight  of  material 
is  taken  from  the  vine.  With  three  toppings  this  varied  from  3724 
pounds  per  acre,  with  the  vigorous  Tokays,  during  1916,  to  1615 
pounds,  with  the  weakened  Carignane,  during  1917.  It  averaged  2598 
pounds  for  both  varieties  and  both  years.  A  single  topping  removed 
from  206  pounds  per  acre  with  Carignane  to  1700  pounds  with  Tokay. 
This  large  amount  of  material  seems  sufficient  to  account  for  a  weak- 
ening of  the  vine.  That  it  is  not  the  only  factor,  however,  is  shown  by 
the  fact  that  three  pinchings  which  removed  a  negligible  weight  of 
material  was  in  some  cases  more  weakening  than  one  topping  which 
removed  more  than  500  pounds  of  shoots  and  foliage  from  an  acre 
The  reason  is  discussed  on  page  379. 

TABLE  LTI 

Material  Eemoved  by  Topping 

(Weight  of  shoots  removed,  in  pounds,  per  acre) 

12  3  Total 

Carignane,  1916  605  1,296  707  2,608 

Tokay,  1916  749  1,275       ■       1,700  3,724 

Average,  1916  677  1,286  1,204  3,166 

Carignane,  1917  614  795  206  1,615 

Tokay,  1917  533  1,128  782  2,443 

Average,  1917  574  962  494  2,029 


TOPPINO   AND  PINCHING   VINES  375 

5.  Cost  of  Pinching  and  Topping. —The  cost  of  the  operations  is 
shown  in  Table  4.  The  cost  of  topping  was  on  the  average  about  30 
per  cent  greater  than  that  of  pinching.  The  cost  of  one  pinching  was 
less  than  two  dollars  per  acre  and  would  be  counterbalanced  by  a 
small  increase  of  crop.  The  cost  of  topping  three  times  was  nearly 
ten  dollars  per  acre  and  would  require  an  increase  of  about  1300 
pounds  of  grapes,  to  reimburse  for  the  labor  used,  at  the  price  for 
which  the  crop  was  sold. 


TABLE  IV 

Cost  of  Topping  and  Pinching 

Per  a  ore 


Time  in  hours 


1916: 

Pinching  Carignane  6.1  10.0  15.1 

Pinching  Tokay  10.0  19.3 

Topping  Carignane  7.2  13.8  12.2 

Topping  Tokay  8.0  17.3  20.0 

1917: 

Pinching   Carignane    6.2  8.1 

Pinching  Tokay   9.1  12.8 

Topping    Carignane    9.5  6.3 

Topping  Tokay  13.3  14.0 

Average  cost  per  acre  at  25  cents  per  hour: 

Once  Twice  Three  times 

Pinching   $1.91  $4.40  $7.86 

Topping  2.38  6.27  9.55 


6.  Effect  on  Weight  of  Crop. — The  benefit  usually  expected  from 
summer  pruning  is  an  increase  in  the  crop.  Pinching  once  increased 
the  crop  of  Carignane  about  16%  the  first  year,  but  decreased  it  about 
11%  the  second  year.  Pinching  once  increased  the  crop  of  Tokay 
nearly  5%  and  pinching  three  times  about  11%  the  first  year  but 
decreased  it  16%  and  21%,  respectively,  the  second  year.  Topping 
once  increased  the  crop  of  Tokay  8.5%  the  first  year  but  decreased  it 
about  32%  the  second  year.  In  all  other  cases  for  both  years  and 
for  both  varieties  there  was  a  decrease  of  crop.  In  all  cases,  the  total 
crop  for  the  two  years  was  less  on  the  pinched  and  topped  vines  than 
on  the  check  where  no  summer  pruning  was  done,  except  in  case  of 
pinching  once  on  the  Carignane  (see  Table  5). 


376  UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 

TABLE  V 

Effect  on*  Weight  of  Crop 

(Yield  in  pounds  per  acre  of  first  and  second  crop) 

None  Once  Three  times 

1916: 

Pinching,    Carignane    27,447  31,644  27,246 

Pinching,  Tokay  21,117  22,899  23,463 

Topping,  Carignane  27,447  27,090  18,351 

Topping,  Tokay    21,117  22,437  16.132 

1917: 

Pinching,  Carignane    24,360  21,600  19,920 

Pinching,  Tokay  19,200  16,140  15,120 

Topping,  Carignane   24,360  19,500  12,090 

Topping,  Tokay    19,200  13,140  11.670 

(In  per  cent  of  crop  of  untreated  vines) 

1916  1917  Total   1916-1917 

, » ,. » „ * , 

None         1  3         None         1  3        Xone         1  3 

Pinching,  Carignane  100  115.6  88.5  100  88.7  81.8  100  102.2  85.2 

Pinching,  Tokay  100  104.6  111.1  100  84.1  78.7  100  94.4  94.9 

Topping,  Carignane....  100  96.7  67.9  100  80.1  49.6  100  88.4  58.8 

Topping,  Tokay  100  108.5  76.4  100  68.2  60.8  100  88.4  68.6 

7.  Effect  on  Second  Crop. — As  summer  pruning  encourages  the 
growth  of  laterals,  it  is  supposed  to  increase  the  weight  of  second-crop 
grapes,  all  of  which  are  borne  on  laterals.  In  most  cases,  an  actual 
increase  was  found  but  it  was  not  very  large.  Where  the  vines  were 
topped  three  times  there  was  an  actual  decrease  of  the  weight  of 
second  crop  (see  Table  6). 

TABLE  VI 
Effect  on  Second  Crop  of  Carignane 

Total  per        2d  crop       Per  cent  of 
Method  vine,  lbs.  lbs.  total 

1916: 

No   pruning    48.8  12.6  25.8 

Pinching,  1  52.7  16.8  31.9 

Pinching,  3  45.4  14.7  32.4 

Topping,  1  45.2  13.9  30.8 

Topping,  3  31.1  9.7  31.2 

1917: 

No  pruning  40.6  4.5  11.1 

Pinching,  1  36.0  7.4  20.6 

Pinching,  3  33.2  5.1  15.4 

Topping,  1  32.5  4.8  14.8 

Topping,  3  20.2  1.7  8.4 

8.  Effect  on  Sugar  Content. — It  is  a  well-recognized  fact  that  as 
a  rule  the  sugar  content  of  the  grapes  varies  inversely  with  the  crop 


TOPPING    AND   I'INCIIIMG   VI N JOS 


:;77 


and  directly  with  the  vigor  of  the  vine.  The  low  sugar  content  of  the 
fruit  in  1916  of  the  vines  which  were  pinched  once  (14%  less  than 
that  of  the  unpruned  vines)  is  therefore  accounted  for  hy  the  larger 
crop  which  was  15.6%  more.  These  two  tendencies,  however,  in  most 
cases  tend  to  neutralize  each  other.  The  summer  pruning  by  weaken- 
ijig  the  vines  tends  to  lower  the  sugar  content,  but  by  decreasing  the 
crop  it  tends  to  raise  the  sugar  content.  The  net  result  is  fairly  con- 
stant sugar  content  in  the  various  lots.  An  exception  to  this  is 
shown  in  the  last  experiment  where  the  heavy  summer  pruning  of 
three  toppings  weakened  the  vines  so  much  that  the  sugar  content 
was  low  in  spite  of  the  small  crop  (see  Table  7). 

TABLE  VII 

Effect  on  Sugar  Content  (Carignane) 

Bal.  1916  Bal.  1917 

i : * .,         , A >        Average 

1st  crop        2d  crop        1st  crop        2d  crop     (weighted) 

No   pruning   22.8  18.8  22.4  15.8  21.7 

Pinching,  1  19.8  16.8  22.1  16.4  19.9 

Pinching,  3  20.5  15.3  21.9  17.0  19.8 

Topping,  1  21.5  17.3  21.5  17.4  20.5 

Topping,  3  19.0  15.5  17.4  15.8  17.6 


TABLE  VIII 
Gains  and  Losses  from  Pinching  and  Topping,   Per  Acre 

1916  1917 

Cost  of  Cost  of  Total  loss 

treat-  Gain  or                         treat-  Gain  or  in  two 

Crop  value        merit  losst      Crop  value  ment  losst  years 

$                  $  $                  $                 $                      $  $ 

Carignane  :* 

No  summer  pruning  206        183        

Pinching  once 206  1.53  -1.53  160  1.55  -24.55  -26.08 

Pinching  3  times ....  184  7.80  -29.80  146  6.08  -43.08  -72.88 

Topping  once  192  1.80  -15.80  140  2.38  -45.38  -61.18 

Topping  3  times  ....  115  8.30  -99.30  70  7.40  -120.40  -219.70 

Tolcay  :* 

No  summer  pruning  158        144        

Pinching  once  172  2.25  +11.75  121  2.28  -15.28  -3.53 

Pinching  3  times...  176  9.60  +S.40  113  7.98  -38.98  -30.58 

Topping  once  168  2.00  +8.00  99  3.33  -48.33  -40.33 

Topping  3  times  ....121  11.33  -37.00  88  11.15  -67.15  -104.15 

t  Figures  preceded  by  +  represent  gain;  by  -,  loss. 
*  The  value  of  the  crop  was  calculated  on  the  basis  of  $15  per  ton,  the 
price  for  which  it  was  sold.  In  estimating  the  value  of  the  Carignane  grapes 
this  price  was  reduced  in  proportion  to  the  difference  between  the  Balling  degree 
of  the  grapes  of  the  particular  experiment  and  that  of  the  grapes  of  the 
untreated  rows.  The  loss  of  the  Carignane,  therefore,  represents  loss  both  in 
quantity  and  quality;  of  the  Tokay,  only  in  quantity  and  the  cost  of  the 
summer   pruning. 


378 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


9.  Gains  and  Losses. — Tf  we  consider  the  differences  in  quantity 
of  crop  and  quality,  as  measured  by  the  sugar  contents,  and  deduct 
the  cost  of  the  operations  there  was  a  loss  in  all  cases  from  all  forms 
of  pinching  and  topping  during  the  two  years.  This  loss  varied  from 
$3.53  per  acre  for  the  Tokay,  which  were  pinched  once,  to  $104.15, 
where  they  were  topped  three  times.  The  slight  gains  in  crop  with 
the  Tokay  in  1916  were  in  all  cases  more  than  counterbalanced  by  the 
losses  during  1917.  There  was  in  no  case  any  gain  with  the  Carignane 
and  the  total  losses  for  the  two  crops  varied  from  $26.08  in  the  case  of 
one  pinching,  to  $219.70  in  the  case  of  three  toppings  (see  Table  8). 

10.  Effect  on  Vigor  of  Vines. — Under  conditions  favorable  to  bear- 
ing, the  most  vigorous  vines  will  produce  the  most  grapes.  Any  de- 
crease of  vigor,  therefore,  diminishes  the  possibilities  of  bearing. 
Under  conditions  of  soil,  climate,  or  variety  unfavorable  to  bearing, 
a  moderate  decrease  of  vigor,  on  the  other  hand,  may  result  in  larger 
crops.     The  conditions  of  these  experiments  were  of  the  former  kind. 

The  vigor  of  the  vines  was  estimated  by  weighing  the  material 
removed  at  each  winter  pruning.  This  is  perhaps  as  accurate  a  method 
as  could  be  devised,  as  the  weight  represents  both  the  volume  of  the 
growth,  and,  to  some  extent,  its  composition.  The  more  vigorous  and 
healthy  the  vine,  the  better  it  nourishes  and  matures  its  wood.  The 
better  nourished  and  matured  the  wood,  the  more  reserve  food  sup- 
plies it  contains  and  therefore  the  higher  its  specific  gravity. 

Table  9  shows  the  results  of  the  weighings,  and  calculations  of  the 
relative  vigor  of  the  vines  of  the  various  experiments  expressed  in 
percentages  of  the  vigor  of  the  comparison  rows. 


TABLE  IX 

Effect  on  Vigor  of  Vines 
(Average  weight  of  primings  per  vine) 

1916 


2 

1  Per  cent 

Experiment  lbs.  of  check 

Carignane,  no  summer  pruning  5.28  100.00 

Carignane,  pinched  once  5.11  96.80 

Carignane,    pinched  three  times..  4.51  85.40 

Carignane,  topped  once  4.70  89.00 

Carignane,  topped  three  times  ....  3.64  68.9 

Tokay,  no  summer  pruning  ....  6.62  100.0 

Tokay,  pinched  once  6.25  94.4 

Tokay,  pinched  three  times  ....  5.13  77.5 

Tokay,  topped  once  6.13  92.6 

Tokay,  topped  three  times  4.08  61.6 


3 

lbs. 

5.23 

3.67 
3.16 
3.04 
1.63 
5.11 
4.16 
3.44 
3.47 
1.96 


1917 


4 
Per  cent 
of  check 

99.1 

69.6 

59.9 

57.6 

30.8 

77.2 

62.8 

52.0 

52.3 

29.5 


5 

Per  cent 
of  1916 

99.1 

71.8 
70.1 
64.7 
44.8 
77.2 
66.6 
67.1 
56.8 
48.0 


19  16 

1917 

22.8 

5.6 

37.2 

22.5 

48.0 

7.4 

47.7 

38.4 

70.5 

TOPPING  AND  PINCHING   VINES  379 

The  percentage  columns  show  that  in  all  cases  summer  pruning 
decreased  the  vigor  and  that  this  decrease  was  much  greater  the  second 
year  than  the  first  (see  columns  2  and  4,  Table  9  and  Table  10). 

TABLE  X 

Loss  op  Vigor  of  Vines 

(In  per  cent  of  1916  check  rows) 

Carignane  Tokay 

1916  1917 

No  summer  pruning .9 

Pinching  once  3.2  30.4 

Pinching  three  times  14.6  40.1 

Topping  once    11.0  42.4 

Topping  three  times  31.1  69.2 

The  percentage  of  loss  of  vigor  in  Table  10  for  1916  and  1917  is 
found  by  subtracting  the  percentages  of  growth  in  columns  2  and  4 
in  Table  9  from  100. 

The  total  loss  of  vigor  for  1917  is  made  up  of  the  loss  due  to  a  less 
favorable  season,  the  loss  due  to  the  effect  of  summer  pruning  in  1917, 
and  the  loss  due  to  the  residual  effect  of  summer  pruning  in  1916. 

The  check  rows  of  Tokay  produced  only  about  three-quarters  the 
growth  in  1917  that  they  did  in  1916.  The  check  rows  of  Carignane, 
however,  were  practically  as  vigorous  in  1917  as  in  1916.  In  the  latter 
case,  therefore,  the  observed  weakening  of  the  summer  pruned  rows 
may  be  considered  as  uninfluenced  by  the  season.  The  observed  weak- 
ening is  much  more  than  would  be  found  if  there  were  the  same  per- 
centage of  weakening  the  second  year  as  the  first.  The  excess  is  there- 
fore a  residual  effect  of  the  summer  pruning  of  the  previous  year. 

A  consideration  of  Tables  9  and  10  shows  that  there  was  a  decrease 
of  vigor  in  all  cases  of  summer  pruning,  varying  from  the  negligible 
amount  of  3.2%  due  to  one  pinching  of  Carignane  for  one  year  to  the 
extreme  degree  of  weakening  indicated  by  70.5%  due  to  three  toppings 
of  Tokay  on  each  of  two  consecutive  years. 

The  direct  weakening  from  pinching  once  was  very  small  and 
much  less  than  from  pinching  three  times  the  first  year.  During  the 
second  year  there  was  a  considerable  weakening  from  pinching  of  both 
kinds  and  but  little  difference  whether  the  vines  were  pinched  once 
or  three  times.  This  contrast  between  the  two  years  may  be  explained 
by  the  fact  that  the  late  new  succulent  growth  induced  by  the  repeated 
pinchings  was  destroyed  by  early  autumn  frosts  the  first  year,  while 
the  long  dry  autumn  of  the  second  year  allowed  all  the  growth  to 
mature. 


:;si) 


UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 


The  same  explanation  may  account  for  the  fact  that  one  topping 
which  might  he  expected  to  he  more  weakening  than  several  pinchings 
as  it  removes  far  more  foliage,  was  actually  less  weakening  than  three 
pinchings,  especially  during  the  first  year. 

Three  toppings  were  in  all  cases  extremely  detrimental  to  the  vigor 
of  the  vines  with  hoth  varieties  and  in  both  years. 

The  variations  in  vigor  of  the  different  lots  is  shown  clearly  by 
figures  1  and  2.  Figure  2  is  a  photograph  of  five  piles  of  canes,  each 
consisting  of  all  the  material  removed  in  winter  pruning  a  row  of 


Pi 


[>:>. 


Ti 


T3 


Fig.    1 
All  the  canes  removed  in  winter  pruning  five  typical   vines  in   1917. 


Carignane  vines  in  December,  1917.  Figure  1  is  a  photograph  of  all 
the  canes  removed  in  the  pruning  of  adjacent  single  average  vines  from 
each  row. 


TOPPING   AND   PINCHING   VINKS 


381 


Ts  Ti  Ps  pi  C 

C   =  No  summer  pruning.  P»  =  Pinched  three  times. P1  ^  Pinched  once. 

T3  =  Topped  three  times.  T'  =  Topped   once. 

Fig.  2 
All  the  canes  removed  in  winter  pruning  five  typical  rows  in  1917. 

11.  Composition  of  the  Mature  Wood. — Directly  after  pruning  the 
vines  in  1917,  samples  of  the  canes  were  taken  for  analysis.  These 
samples  were  chosen  in  such  a  way  as  to  make  them  representative  and 
comparable.  They  were  analyzed  at  the  Viticultural  Laboratory  at 
Berkeley  by  Mr.  J.  R.  Zion.  Four  samples,  each  representing  a 
different  row,  were  taken  from  each  experiment  lot  and  analyzed 
separately. 

The  averages  of  the  sets  of  analyses  are  given  in  Tables  XI,  XII, 
and  XIII. 


TABLE  XI 

Composition  of  the  Mature  Wood  (Canes) 

(Calculated  on  the  dry  weight) 


Experiment 

if 

»\V 

Moisture 

Starch 

Sugar 

■ . 
Protein 

Ash 

Carignane: 

Check 

11, 

12, 

16 
17 

43.9 
42.9 

21.89 
25.13 

4.66 

4.10 

3.18 
2.82 

1.92 

Pinched 

1  ... 

1.87 

Pinched 

3... 

13, 

18 

45.5 

24.08 

4.84 

2.76 

2.12 

Topped 

1    ... 

14, 

19 

46.9 

25.67 

4.84 

3.09 

2.30 

Topped 

3   ... 

15, 

20 

48.7 

23.60 

5.80 

4.73 

2.30 

ToJcay  : 

Check 

31, 

32, 

3(5 
37 

47.7 
47.3 

23.39 
23.54 

5.04 
3.72 

2.71 

2.87 

2.48 

Pinched 

1  ... 

2.76 

Pinched 

3... 

33, 

38 

48.2 

23.49 

l.ss 

2.46 

2.79 

Topped 

1    ... 

34, 

39 

48.9 

21.69 

6.00 

2.96 

2.94 

Topped 

3   ... 

35, 

40 

52.8 

22.05 

5.28 

2.87 

3.04 

382 


UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 


The  moisture  contents  are  lowest  and  the  starch  contents  highest 
in  the  cases  where  the  vines  were  pinched  once.  This  indicates  a  more 
perfect  maturity  of  the  wood.  All  other  treatments  increased  the 
moisture,  indicating  less  perfect  maturity  in  proportion  to  the  amount 
of  pruning.  The  improved  condition  of  the  wood,  following  one 
pinching,  is  marked  only  in  the  Carignane  and  the  injurious  action  of 
the  other  treatments  is  more  marked  in  the  Tokav. 


TABLE  XII 

Averages  for  the  Two  Varieties 

(Calculated  on  the  dry  weight) 

%  %  %  %  % 

Experiment  Row  Moisture  Starch  Sugar  Protein  Ash 

Cheek   11,16,31,36  45.8  22.64  4.85  2.94  2.20 

Pinched    1  12,17,32,37  45.1  24.33  3.91  2.84  2.31 

Pinched    3  13,18,33,38  46.8  23.78  4.86  2.61  2.45 

Topped    1  14,19,34,39  47.9  23.68  5.42  3.02  2.62 

Topped    3  15,20,35,40  50.7  22.82  5.54  3.80  2.67 

TABLE  XIII 

Averages  of  the  Two  Varieties 
(Calculated  on  the  weight  of  the  fresh  samples) 

Experiment     Dry  matter  Starch  Sugar  Protein  Ash 

%  %  %  %  % 

Check    54.2-  12.27  2.63  1.59  1.19 

Pinched    1 54.9  13.36  2.15  1.56  1.27 

Pinched    3 53.2  12.65  2.59  1.39  1.30 

Topped    1 52.1     •  12.34  2.82  1.57  1.37 

Topped    3 49.3  11.25  2.73  1.87  1.32 

The  ash  of  the  Carignane  samples  is  affected  in  a  manner  parallel 
to  that  of  the  moisture.  Pinching  once  decreased  it,  while  other  treat- 
ments increased  it  in  accord  with  their  severity. 

According  to  L.  du  Sablon1  the  proportion  of  ash  in  the  dry  matter 
of  plant  stems  decreases  with  maturity.  These  ash  determinations 
then  indicate,  like  the  moisture  determinations,  that  tipping  once 
favored  the  maturity  of  the  wood  of  the  Carignane  but  that  all  severer 
summer  pruning  delayed  maturity.  All  forms  delayed  maturity  in 
the  Tokay. 

L.  du  Sablon  states  further  :2  ' '  There  is  an  absolute  increase  of  the 
ash  with  age,  but  as  the  organic  matter  increases  more  rapidly  than 
the  mineral  matter,  the  proportion  of  the  latter  diminishes."  Tables 
XII  and  XIII  show  that  the  greater  contents  of  ash  in  the  wood  of 
the  vines  summer  pruned  is  not  only  relative  but  absolute.    A  general 

i  Traite  de  Physiologie  Vegitale  et  Agricole,  p.  285. 
2  Loc.  cit.,  p.  286. 


TOPPINCi   AND  PINCHING   VINK.S 


383 


characteristic  of  diseased  plants  is  an  increase  of  ash.  It  seems  prob- 
able, therefore,  that  summer  pruning  not  only  interferes  with  the 
proper  maturing  of  the  wood  but  has  some  pathological  effect  also. 


W  s  V 


W  8  V 


CHECK 


.CAR! 


GNANE     11916 


CAR  I 


GN  AN  E 


p« 


OKAY     1 


1917 


91  6 


OKAY     1 


P3 


917 


BIB 


Tl 


B  B  B 


ii 


i 


T  3 


EFFECT   OF    SUMNER   PRUNING 

on    CROP    .    VALUE    AND   VIGOR 

W   WEIGHT    OF   CROP      S   VALUE    OF   CROP    V   VI  GOP   OF   VINES 
Pi    PINCHED  ONCE    P3   PINCHED   3  TIMES  Tl  TOPPED  ONCE  Ts  TO  P  PED  3  TIMES 


Fig.    3 

SUMMARY 

A  summary  of  the  results  of  this  investigation  is  given  graphically 
in  figure  3. 

Each  experiment  is  represented  by  a  group  of  three  black  columns 


384  UNIVERSITY   OP    CALIFORNIA — EXPERIMENT    STATION 

for  1916  and  another  group  of  three  for  1917.  The  first  column  of 
each  group  represents  the  weight  of  crop,  the  second,  the  value  of  this 
crop  minus  the  cost  of  the  summer  pruning,  and  the  third,  the  vigor 
of  the  vines. 

There  was  in  all  cases  a  net  loss  in  value  of  crop  and  vigor  of 
vines  for  the  two  years  as  follows : 

Net  Loss  in  Two  Years  prom  Summer  Pruning 

Carignane  Tokav 

, * > '' N 

Crop,  dollars   Vigor,         Crop,  dollars    Vigor, 
per  acre      per  cent  per  acre       per  cent 

One  pinching   26  29.5  4  14.4 

Three  pinchings  73  39.2  31  25.2 

One  topping  61  41.5  40  24.9 

Three  toppings  220  68.3  104  47.7 

CONCLUSIONS 

We  may  conclude  from  these  results  that  both  pinching  and  topping 
are  harmful  under  conditions  similar  to  those  under  which  the  experi- 
ments were  conducted. 

That  very  heavy  topping  continued  year  after  year  may  almost 
ruin  a  vineyard. 

That  topping  is  more  harmful  than  pinching  but  that  even  the 
latter,  contrary  to  the  usual  belief,  is  both  weakening  and  detrimental 
to  the  crop. 

It  should  not  be  overlooked,  that  these  conclusions  apply  only  to 
the  conditions  of  the  experiments. 

Many  varieties,  when  growing  in  excessively  rich  soil  abundantly 
supplied  with  nitrogen,  humus,  and  water,  are  often  unfruitful  owing 
to  an  excess  of  vigor,  and  moderate  summer  pruning  might  result  in 
better  crops  without  dangerously  weakening  the  vines. 

Some  varieties,  moreover,  produce  few  fruit  buds  on  the  main  canes 
but  produce  them  abundantly  on  the  laterals.  Moderate  pinching  or 
even  topping  in  such  cases  might  be  necessary  to  promote  the  growth 
of  fruitful  laterals. 

Topping  or,  better,  pinching,  is  also  necessary  under  some  condi- 
tions where  heavy  winds  are  liable  to  break  off  whole  shoots.  It  should 
be  done,  however,  with  a  realization  that  the  only  object  in  view  is  to 
prevent  a  more  serious  injury. 

Probably  four-fifths  of  the  topping  practiced  in  California  is  inad- 
visable. It  should  never  be  applied  to  Muscats  or  similar  vines  of 
weak  growth  nor  to  any  varieties  when  not  excessively  vigorous.  It  is 
less  harmful  to  young  vines  than  old  and  is  most  useful  for  two  and 
three-year-old  vines  to  get  them  into  the  proper  shape  before  they  bear. 


